Cyclostratigraphic analysis of pelagic carbonates at Monte dei Corvi (Ancona, Italy) and astronomical correlation of the Serravallian-Tortonian boundary

摘要

Spectral analysis of high-resolution calcium carbonate data from a 2-m.y.-long section from the upper Miocene pelagic limestone-mark sequence at Monte dei Corvi, Italy, indicates orbital forcing of depositional cycles at frequencies corresponding to eccentricity, obliquity, and precessional cycles. Identification of these Milankovitch cycles, dated by Ar-40/Ar-39 ages from two biotite-rich volcanic-ash layers within the section, allows us to correlate this section with the astronomical time scale by matching low-frequency variations in calcium carbonate content with the orbital eccentricity. This correlation yields precise numerical ages for any stratigraphic level within the analyzed section, including the two volcanic-ash layers and the Serravallian-Tortonian boundary, dated here as 11.32 Ma. The eccentricity-based correlation also allows us to tune the data, resulting in enhanced power in the obliquity and precessional frequencies, supporting the initial hypothesis of orbital control of these lithologic cycles. [References: 19]